This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have designed and constructed a novel mass spectrometer for profiling phosphorylation sites on proteins. The instrument is designed to be up to three orders of magnitude more sensitive than current commercially available instrumentation. We have tested the prototype and found that it works as per its design and our simulations. We have applied for and being granted a US patent for our novel design. A paper describing this work has been published: S. Myung, H. Cohen, D. Feny[unreadable], J.C. Padovan, A.N. Krutchinsky, B.T. Chait. "High-capacity ion trap coupled to a time-of-flight mass spectrometer for comprehensive linked scans with no scanning losses", International Journal of Mass Spectrometry 2010. In press